I’ve recently started a new job at an American start-up company. My position in the company is the one of Technical Lead – the person responsible for the selection of technologies around which the projects are being built. Since we’ll be doing mostly web development we’ve had a long kick-off discussion with the company’s CTO about the direction which we should initially take. He had PHP in mind, but I convinced him that Ruby or Python would make much better platforms for our futures apps. So he tasked me to research the two leading frameworks in the Ruby and Python land – namely Ruby on Rails 3 and Django 1.3. I had a week to prepare some prototypes with both and create on overview for my boss. I had some experience with Rails 2 a few years back and I have fairly decent knowledge of Ruby. My Python is not as fluent (admittedly), but still – I’ve played a lot with Python recently. Django, however, was completely new to me. In this article I’ll try to compare the frameworks in a totally friendly way; if you’ve expected an epic flame war post you may very well stop reading here. I’m obviously no Rails/Django guru, so if I’ve written something that is wrong – please feel free to correct me.
Please, keep in mind that a short comparison article cannot even begin to scratch the immense power and complexity of such frameworks. The overview, that you’ll find here is a bit on the superficial side, but it should give you enough pointers to get you started.
Hopefully this article will be useful to people that are in the same boat as was – picking between Rails and Django.
Setup & Getting started
Linux & OSX
The recommended (by me) way to install Ruby and Ruby on Rails 3.x is via RVM. RVM allows you to have several version of Ruby installed at the same time and to easily switch between them. It also allows you to create gem sets, which are quite handy in testing. After you’ve installed RVM it’s easy to install any Ruby interpreter and Rails. This example shows how to get RVM, MRI 1.9.2 and Rails current (3.0.9):
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Since RVM builds Ruby environments from source you might need to install a few dependencies first. After you’ve install RVM it will output those packages as instructions.
If you’re using Z Shell (like me) you should replace .bash_profile with .zshenv or .zshrc.
While there are many ways to get Ruby on Rails installed on a Windows host, the simplest is certainly to use the RailsInstaller. It has only one little drawback – currently it comes with Ruby 1.8.7 bundled, but the recent beta already features Ruby 1.9.2.
Your first Rails app
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As you can see the structure of a Rails project consists of quite a few folders and files. This is a bit intimidating at first, but becomes quite valuable once you’ve used to the predefined structure. You’ll find a good overview of the structure here.
Open your browser and type http://localhost:3000 as the url. If everything is OK you’ll see a Rails welcome page.
At this point you should probably either start playing with scaffolding or read the rest of this article and start playing with scaffolding afterwards :–) For instance you can try:
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Open your browser and type http://localhost:3000 as the url. “Magic” like this made Rails famous originally.
By default Rails apps use SQLite as a database backend, so might have to install it as well.
The rails script is useful for various tasks – code generation, plug-in installation, running a rails console, running a development web server, etc.
I prefer to install django from the distribution’s package manager. On a Red Hat distro like Fedora I would do:
And on a Debian system:
The Bitnami Django stack is the simplest way to get Django and everything that it requires in a single step.
Your first app
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Compared to Rails, Django created a much simpler project structure. There are only four files in here and only two are actual Django configuration files – settings.py and urls.py. manage.py is just a script useful for managing some aspects of the project (similar to the rails script) – it can sync the model with the database, run a development web server, run a django console, etc.
To test the new project open http://127.0.0.1:8000/ in your browser.
Features at a glance
Convention over configuration
People seem to underestimate the importance of CoC in practice initially – it makes it a lot easier to reason about a project and a lot easier to configure the project. On the other hand if some of the defaults don’t work for you – you’d have to jump through some hoops. Recent versions of Rails, however, have made it a lot easier to tweak the defaults.
All in all I feel that CoC is a big win for developers and I guess many people share my opinion since CoC can now be found in many other frameworks as well.
MVC to the bone
Rails is a classical Model-View-Controller full stack web framework – it handle all aspects of a typical web application. What separates it from most of the MVC frameworks around is the heavy emphasis on REST. The domain objects are treated as resources and could be handled in a uniform manner using just the standard HTTP verbs like GET, PUT, DELETE, POST. REST is extremely good fit for data driven applications.
As usual the model houses the application’s business logic, the controller invokes functionality from the model layer and feeds the resulting data to the view layer, which display the data in a meaningful way to the user.
The model layer is the home of your domain objects and the business logic surrounding them. Domain objects (a.k.a. entities) are mapped to database tables (at least in RDBMS). Unlike most object relational mappers Rails’s ActiveRecord (the default ORM; could be substituted with something else if you wish) doesn’t require you to explicitly declare the structure of the objects, but rather extracts it automatically from your DB table definitions. A simple class, modeling an application user might look like this:
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Note that the validation methods are entirely optional (but highly recommended) – the class could have very well had an empty body. Rails would know to look for a table named Users in the database and extract the field information from it.
Rails generates automatically for us “finders” that we can use to make queries about objects in pure Ruby. It also provides an elegant DSL to express relationships between various model classes (belongs_to, has_many, etc)
In the view layer Rails has traditionally relied on HTML templates with Ruby code embedded in them (html.erb). There are a lot of community contributed alternatives, however, with HAML being the most prominent one. On a similar note Rails allows you to use SASS as a replacement for traditional CSS.
Another centerpiece in Rails is the “Don’t Repeat Yourself”(DRY) principle. In the view layer partial templates, layouts and helpers are some of the tools available to help you abide by that principle. You’ll certainly make heavy use of them in your applications so you should pay them some special attention.
Everyone that has done some serious programming knows that it’s not realistic to presume that the initial database schema won’t ever change – fields get added/removed, new tables get introduced, etc. All those changes are commonly referred to as “migrations” and traditionally every team unrolls its own handling of the problem. On my last job I was tasked at some point to write a tool in Java that analyzed a config file and a directory structure filled with SQL scripts and applied them selectively to various target databases. In Rails you get this functionally for free – you can express your migrations as simple Ruby scripts and you can use rake to generate the appropriate SQL statements for any supported database. Here’s a simple migration script, that creates the Users table:
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The up method gets invoked when the migration is applied and the down method gets invoked when it’s reverted. Rails 3.1 will offer even more elegant migrations. To execute all migrations:
Ajax from within
Making and handling AJAX requests in Rails is generally very easy – a big advantage in today world ruled by rich and dynamic web UIs.
Rails is extendable through a multitude of community supplied plugins that could add incredible functionality to your apps for free. Some of my favorite plugins are jQuery for Rails, client side validations and Rails Admin.
Testing is not optional
What I particularly like about Rails is that it heavily promotes testing your code. All of the Rails generators would generate test stubs, that you’ll do good to fill in. Rails supports all major Ruby test frameworks – Test::Unit, RSpec, Cucumber. You have fixtures support, test database support, the ability to run unit and functional test separately. I don’t recall using any other framework that pays as much attention to having tests as Rails and for that I can only congratulate the Rails team.
Compatibility with Ruby versions
There are two major version of Ruby out there presently – Ruby 1.8.7 and Ruby 1.9.2. Ruby 1.9.2 offers substantial language and performance improvements, so you should be pleased to hear that Rails supports both major Ruby versions. Rails 4.0 will drop support for Ruby 1.8.x.
Rails can also be run on top of JRuby and Rubinius.
The most common deployment options for Rails are currently Apache HTTPD or NginX and Phusion Passenger (mod_rails). People shopping for cloud Rails deployment should definitely take a look at Heroku.
Rails also runs on alternative Ruby implementations like JRuby and Rubinius (as mentioned above), that offer exciting new possibilities. For instance using JRuby allows you to deploy a Rails app into a Java application server like JBoss or Glassfish and to tap into all those great Java libraries and frameworks around. Using JRuby also gives you the opportunity to deploy your apps on Google’s App Engine.
A simpler project layout
While I had some experience with Rails from a couple of years ago, Django was something totally new to me. I expected it to be more or less Rails for Python, but when I created my first Django app I was surprised to see that the project folder consisted of only three files (I’m obviously not counting the python package file init.py).
My initial surprise aside it turned out that most differences were just superficial and that Django and Rails have quite a lot of similarities. I’ll, however, speak a bit more about the different stuff than the similar stuff.
MVC(MTV), Django style
While Django is a MVC controller framework as well, it’s built around a different mindset. Django is totally configurable and minimalistic framework that empowers the developers to tailor it to their needs.
A Django project is comprised of autonomous and reusable apps. Apps on the other hand are comprised of models, views and templates. Django differs a bit in terminology with Rails – the Rails controllers are views in Django and the Rails views are called templates in Django. You can sometimes hear that Django is a Model-Template-View framework – that shouldn’t confuse you. Although the terminology is different the principles are the same.
Django’s default ORM is somewhat reminiscent of frameworks like Hibernate. Entity classes declare explicitly the all the attributes. Let’s consider again the User model class:
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Both approaches have their strengths and weaknesses an usual. In Django’s case we have increased verbosity, but on the other had we don’t have to inquire the database to figure out the exact definition of model records.
Like in Rails we get useful “finders” that can be used to query for model objects in pure python (as opposed to using sql).
In the template layer
While ERB is basically HTML with Ruby embedded in it, Django features a custom templating language with it’s own (extendable) tag library. This generally means that Django templates tend to be a bit cleaner than Rails’s templates, since you’re not allowed to abuse them very much. On the other hand you can do virtually anything by embedding code directly in a template, so as usual – each design decision has its pros and cons.
Django supports alternative templating libraries, so you’re covered in case you don’t like the default one.
Django also features a powerful form generation/handling facilities that integrate seamlessly with the templating layer. For instance – it very easy to generate a form matching the structure of a domain model object with automatic property validation.
You’re in charge
Django has doesn’t adhere to the Rails CoC philosophy. It’s assumed that developers know best what layout and configurations options make the most sense in their applications. I haven’t played that much with Django yet, but I still haven’t come by two different Django apps that are structured in the same manner. While I understand the benefits of Django’s approach I still prefer Rails’s approach. I’ve worked long enough to know that you’re rarely in the position to make better decisions about the structure and the defaults of your app, than the exceptional developers with huge experience that develop frameworks like Rails and Django.
To illustrate this consider the strong emphasis Rails places on REST. In Django you could certainly use restful access your resources as well, but it’s all up to you. The framework makes no suggestions. You can unroll any URL mapping scheme by simply associating regular expressions in urls.py with callback view functions:
from django.conf.urls.defaults import patterns, include, url urlpatterns = patterns('', url(r'^$', 'djangodemo.views.home', name='home') url(r'^users', 'djangodemo.view.users', name='list_users'))
An url is mapped to the callback function, which in turn either renders a template or directly returns some Http response.
Django has a built-in support to generate an admin UI for your website. This is a very useful feature indeed and is supported in Rails as well through plugins (I’ve mentioned the one I like the best).
One of the few gripes I have with stock Django is that it doesn’t offer an alternative to Rails’s migrations. Luckily there is South – an extension that provides a simple, stable and database-independent migration layer to prevent all the hassle schema changes over time bring to your Django applications. I highly recommend it to everyone planning to use Django.
The great divide
Some of you probably know that Python is currently at a bit of a crossroads. Python 2.x was the stable Python version for many years, but recently it was replaced by Python 3.x. Python 3.x is all around great in my personal opinion, but unfortunately it’s backward incompatible with the older 2.x series. For that reason very few high profile projects still don’t support it – Django is one such project. The current version 1.3 require at least Python 2.4 and will run with every Python up to 2.7. This is a bit of a disappointment since you’ll be missing on a few very cool new features. On a more positive note Python 2.7 did backport some goodies from Python 3, so not all is lost. I’ve read (at totally unofficial places) that Django 2.0 will be targeting Python 3 and I expect it will be available in about a year.
Python is quite mature technology and offers you a nice array of deployment options – Apache, Nginx and my favorite – Google App Engine. Python, being one of the two supported languages on the App Engine (the other one is, of course, Java) makes it very easy to deploy Django apps on the App Engine (though you’ll need the Django support for non-relational databases to be able to use it).
The also the possibility to deploy Django apps on Java or .Net infrastructure using Jython or IronPython.
When you’re selecting the technology for a major project you have to make sure that the technology is in good shape – there is a solid community around it, there is no lack of support, innovation and deployment options.
Both Google trends and stackoverflow.com (by the number of question about tagged with django or rails) indicate that Rails currently has larger community than Django.
I haven’t had any direct communication with the Django community yet, but I’ve found a lot of excellent resources about Django on-line.
Rails has one of the most vibrant, passionate and innovative communities. I’ve had contact with a lot of people from the Rails community and I’m certain that it has played a tremendous role in Rails’s growth.
Traditionally Ruby & Python hackers have been working with just a powerful programmer’s editor like Emacs, vim or TextMate. While there is nothing inherently wrong with this approach (I’m an avid Emacs user myself), I do find IDEs quite helpful when working on larger code bases, with their trademark features such as intelligent autocompletion (aka intellisense), safe refactorings, on-the-fly syntax checking, etc. So here’s what we’ve got:
- RubyMine – hands down the best Ruby and Rails IDE I’ve ever used. The list of features is epic as is the quality of the project. It support Rails 3, git, RSpec, Cucumber, sass, haml and many other cool Ruby/Rails related technologies. Sure, it’s a commercial project, but is priced very reasonably.
- Aptana Studio – a Web development IDE, built on top of the Eclipse platform. Among many other features it supports Ruby on Rails.
- Komodo – an IDE focusing on dynamic programming language. Great support for both Django and Rails development.
- PyCharm – from the same company that develops RubyMine, PyCharm is the king of IDEs when it comes down to Python. It has full featured Django support – there is even autocompletion in the Django templates.
- PyDev – an Eclipse plug-in for Python and Django development.
I have to admit I’m totally biased. Having been a long time Java developer I’ve grown extremely fond of the exceptional IntelliJ IDEA. RubyMine and PyCharm are both based on the IntelliJ platform and bring to the Ruby and Python developers much of the might and magic of IDEA. There are both commercial products, but their price tags are quite low and their quality is great – highly recommended.
I’m not affiliated in any way with any of these products – I just happen to like them that much.
The are LOTS of resources about Rails and Django on-line. Here are just my favorites.
- Rails Guides – best short introduction to Rails ever. Immediately updated for new Rails versions, fantastic starting point for any aspiring Rails developer.
- Rails Tutorial – best Rails 3 book on the market and it even has a free on-line edition. Nice follow up of the Rails Guides.
- RailsCasts – Ryan Bates in true Ruby hero. He has compiled a unique set of high quality Rails screencasts that often illustrate some advanced techniques. And they are all free. We all owe a very big “Thanks!” to Ryan.
- Official Docs – best official project documentation I’ve read. It’s actually so good, that I never (well – almost never) bothered to look for anything else. All my questions were answered by the official documentation.
Choosing Django or Rails is basically a win-win situation – you cannot go wrong. There are too many similarities between the frameworks and the differences are not something paramount.
Rails places a heavy emphasis on convention over configuration, provides you with more defaults and does a can do a lot of heavy lifting for you automagically.
Django on the other hand let’s you specify most configuration details yourself, without making the configuration burdensome (like that of older Java web frameworks).
Rails has always been leading on the way of innovation – constantly integration some of the latest and greatest technologies around (recent examples being jQuery, Coffee Script and SASS). From time to time backward compatibility is sacrificed for the greater good, so that is something that you should consider as well.
Django is certainly much more conservative framework as far as backward compatibility is concerned – after all it still support Python 2.4.
I guess in the end the choice really boils down to two things – whether you like Ruby or Python better and whether you like the defaults imposed to you by Rails.
I’ve planned to write a much longer and detailed article, but it’s summer here and it’s sunday and I’d rather go out and drink a few beers with my friends. Hopefully you’ve enjoyed the article. I’ll try to expand it a bit in the coming days.
P.S. Btw, in case you’re wondering – we’ve picked Rails for our company’s projects. It was a very close call, though, since I really liked a lot of aspects of Django as well.